This invention relates to a laser light emitting probe to permit an incision, a vaporization of living tissue of animal organisms or a thermal therapy, and the producing method of said laser light emitting probe.
Medical treatments such as incisions of living tissue of animal organisms by irradiation with laser light are conspicuous due to its ability of hemostasis in these days. It had been the conventional method that the laser light was irradiated from the fore end of an optical fiber system which is non-contact with the living tissue. But this method causes severe damage to the fore end of the optical fiber system. Therefore, a method which has been utilized lately is as follows; at first, the laser light, after being transmitted into an optical fiber system, is fed into an emitting member of a probe being in contact or non-contact with the living tissue (hereafter "living tissue" is sometimes expressed by "tissue" only). Then the laser light emitted from the surface of the probe is irradiated on the tissue.
The inventor developed many kinds of contact probes which are utilized for various purposes. One embodiment is shown in FIG. 11. This probe is made of sapphire, quartz and the like. Usually, it has a smooth surface and does not have a surface layer. Further, it has a tip end of a tapered conical shape.
Referring to FIG. 11, laser light L is fed by means of an optical fiber 51 into the probe 50, which is of long and narrow conical shape with a round tip end and whose outer surface is smooth. The laser light L passing through the probe 50 is reflected and refracted on an inner surface to reach the tip end, finally is emitted only from the tip end.
In this case, a power density and its distribution of the laser light L are shown as contour lines H and a curve Pd respectively in FIG. 11. Accordingly, it is obvious that the laser light L is concentratedly emitted from the tip end of the probe 50. Therefore, while the thickness (depth) T1 of a coagulation layer C is increased, the laser light does not irradiate effectively to tissue along the side of the probe, then the effect of an incision and hemostasis at the tissue along the side of the probe is reduced. As a result, in case of the incision of hemorrhagic tissue such as liver and the like, the probe must be repeatedly moved along the same incision line little by little. Therefore, the surgery requires much labour and must be done carefully.
Under these circumstances, the inventor found a surface treatment method for the probe; formation a roughened surface of the probe extends the effective area of laser light irradiation, because the laser light is refracted on the roughened surface to be emitted in many directions.
Although it is possible to extend the effective area of the laser light irradiation by means of the above method, its efficiency is not sufficient. In order to compensate the low efficiency of the incision for the tissue along the side of the probe, an output power level from a laser light generator should be enhanced. Further, the high power level laser light causes a severe damage to the tissue. Therefore, this probe is not applicable for the incision of hemorrhagic internal organs.
The inventor had done a lot of research on these defects to find the following.
The effect of the incision at a side part of the incised portion is enhanced by a formation of a rough outer surface of the probe covered with a surface layer having laser light scattering particles. Because, a scattering effect is extended by means of the light scattering particles in the surface layer as well as the roughened surface of the probe.
Referring to FIG. 12, by a probe 50A having said surface layer 50a, a broad laser light irradiation pattern can be obtained, while a depth T2 of a coagulation layer is reduced. Accordingly, the effect of the incision at the side part of the incised tissue is enhanced.
However, some defects still exist in said probe. The first defect relates to hemostasis. Since the laser light is emitted from the tip end more than from the side of the probe, the coagulation layer in the tissue at the side part of the probe is not so deep. Therefore, the effect of the hemostasis shown by the depth of the coagulation is known to be reduced. If there is a blood vessel adjacent to the thin coagulation at the side part of the probe, bleeding is apt to be caused.
The second defect relates to the process of the incision. When the probe starts to move along an incision line, the tissue is incised by the tip end of the probe. Therefore, it is comparatively easy for the probe to move on the surface of the tissue. There remains, however, a difficulty of the probe movement in the tissue at the side part of the probe. In other words, it is easy to start to incise, but it is difficult to continue to incise along the incision line.
Another defect is that it is also difficult to know an incised depth in the tissue, because the probe moves too easily on the surface of the tissue.
On the other hand, such consideration for the hemostasis must not be taken for the incision of less hemorrhagic tissue such as skin, fat layer and the like. In order to compensate the reduced effect of the incision at the side part of the incised tissue, however a high laser power is required. This causes a damage to the tissue. Further, this necessitates a high power and expensive laser light generator. If the laser power remains at a low level, the probe must be moved slowly. Then, a surgery using this probe can not be carried out quickly.